Generally, encoding is a process that a transmitting side performs a data processing for a receiving side to restore original data despite errors caused by signal distortion, loss and the like while the transmitting side transmits data via a communication channel. And, decoding is a process that the receiving side restores the encoded transmitted data into the original data.
Recently, many attentions are paid to an encoding method using an LDPC code. The LDPC code is a linear block code having low density since most of elements of a parity check matrix H are zeros, which was proposed by Gallager in 1962. It was difficult to implement the LDPC code that is very complicated due to the technological difficulty in those days. Yet, the LDPC code was taken into re-consideration in 1995 so that its superior performance has been verified. So, many efforts are made to research and develop the LPDC code. (Reference: [1] Robert G. Gallager, “Low-Density Parity-Check Codes”, The MIT Press, Sep. 15, 1963. [2] D. J. C. Mackay, Good error-correcting codes based on very sparse matrices, IEEE Trans. Inform. Theory, IT-45, pp. 399-431 (1999))
Since the number of 1s of the parity check matrix of the LDPC code is very small, decoding of the parity check matrix of the LDPC is enabled through repetition decoding in case of a large block size. If the block size becomes considerably large, the parity check matrix of the LDPC code shows the performance that approximates a channel capacity limit of Shannon like a turbo code.
The LDPC code can be explained by a (n−k)×n parity check matrix H. And, a generator matrix G corresponding to the parity check matrix H can be found by Equation 1.H·G=0  [Equation 1]
In an encoding/decoding method using an LDPC code, a transmitting side encodes input data by Equation 2 using the generator matrix G having a relation of Equation 1 with the parity check matrix H.c=G·u,  [Equation 2]
where ‘c’ is a codeword and ‘u’ is a data frame.
Lately, a method of encoding input data using the parity check matrix H is globally used instead of the generator matrix G. Hence, as mentioned in the foregoing description, the parity check matrix H is the most important element in the encoding method using the LDPC code.
However, the parity check matrix H having a size approximately exceeding 1,000×2,000 needs lots of operations in the encoding and decoding processes, has difficulty in its implementation, and requires a considerably large storage space.